Why are most rectifiers we use 5 volt(5u4, 5ar4) rather than the more common 6.3 volt heater? Is there a reason for this? Life would be much easier but maybe more prone to mistakes on heater wiring. Anyone know?
This doesn't really answer your question, but contributes: 6.3 Volts comes from the battery era, before widespread electrification, and pre-war lead-acid auto batteries. Same for 12.6 Volts.
When AC mains electricity became more common, any voltage at all was possible, and a coupla volts is about right for valve heaters of all kinds.
All good fortune,
Chris
When AC mains electricity became more common, any voltage at all was possible, and a coupla volts is about right for valve heaters of all kinds.
All good fortune,
Chris
6.3V comes in very suddenly with Car Radio.
Cars had been around, but with little or no electricals. Radio simmered a while before the tube and loudspeaker. Cost was a problem too. But several outfits (notably one later known as Motor-ola) had car radios in 1930. Typically it took a year for something like a new heater voltage to trickle-through the tube factory in bulk, so pencil 1931. Even with heaters (which were still new) on light-battery, B+ was a huge dry battery, so output was limited.
5V rectifiers go back before this to when small amplifier tubes tended to be 2.5V heat (really a better choice if not for those cars) and large amp tubes were 5V (but NOT on the same winding as the rectifier). 4V heat was the way to go in the UK (which also favored 12V car battery decades before the US went that far).
Cars had been around, but with little or no electricals. Radio simmered a while before the tube and loudspeaker. Cost was a problem too. But several outfits (notably one later known as Motor-ola) had car radios in 1930. Typically it took a year for something like a new heater voltage to trickle-through the tube factory in bulk, so pencil 1931. Even with heaters (which were still new) on light-battery, B+ was a huge dry battery, so output was limited.
5V rectifiers go back before this to when small amplifier tubes tended to be 2.5V heat (really a better choice if not for those cars) and large amp tubes were 5V (but NOT on the same winding as the rectifier). 4V heat was the way to go in the UK (which also favored 12V car battery decades before the US went that far).
Indeed, before the lead-acid 6,3V car battery standard, the US used 2,5V and 5V for both rectifier and amplification tubes (2A3, 300B for instance), while Europe standardised on 4V. Types starting with 'A' indicate 4V: AZ1, AZ50, AZ41 are rectifiers, AD1 power triode, AL4 power pentode for instance. After the '6,3V revolution' you would also find 6,3V ('E') rectifiers: EZ40, EZ81. All indirectly heated.
The larger rectifiers became 5V like in the US: ie the GZ34. Maybe somebody can explain why these recs didn't evolve into the new 6,3V standard?
The larger rectifiers became 5V like in the US: ie the GZ34. Maybe somebody can explain why these recs didn't evolve into the new 6,3V standard?
Rectifiers can not be run on the A (car lights) battery because it is grounded. So there never was a need for 6V rectifiers. All the naked-filament US rectifiers are very antique designs. The bases changed but not the guts.
I personally would never use a 6.3V indirectly heated rectifier, unless it was a Damper Diode with lots of insulation from filament to cathode.
I do not trust the filament to cathode interface of a rectifier being powered from the same 6.3V as the input and output amplifier tubes.
One little short and . . . .
As long as we are also talking about car radios, how about those 6.3V Vibrators to pulse a transformer to get B+.
(Early Switching power supplies, no solid state switcher transistors).
I do not trust the filament to cathode interface of a rectifier being powered from the same 6.3V as the input and output amplifier tubes.
One little short and . . . .
As long as we are also talking about car radios, how about those 6.3V Vibrators to pulse a transformer to get B+.
(Early Switching power supplies, no solid state switcher transistors).
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No arguing over personal preferences from my part but there were millions and millions of tube radios in which rectifiers like the EZ80 and the EZ81 were being powered from the same 6.3 V winding as the rest of the tubes. This leads me to believe that cathode to heater failures in these types of rectifiers were not so common, atleast not at a B+ of about 250 to 300 Vdc which was common in tube radios.
U.S. car radios, with vibrators, used the 0Z4 rectifier.
The 5U4G (Octal) is electrically equivalent to the 5Z3 (UX4). The 5Y3 (Octal) is electrically equivalent to the #80 (UX4). Dunno about the 5R4, as that type is intertwined with aviation.
The 5U4G (Octal) is electrically equivalent to the 5Z3 (UX4). The 5Y3 (Octal) is electrically equivalent to the #80 (UX4). Dunno about the 5R4, as that type is intertwined with aviation.
Also note the 5 volt rectifiers came about at the time when battery eliminators were sold for battery powered radios. You could buy a power supply that replaced the A and B batteries at least.
The 12X4 rectifier tube was used in the Dynaco PAS series for many years, and I have never seen any
problems or failures with its filament being on the same winding as the grounded 12AX7 filament circuit.
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I bet it is much cheaper just to connect the filament to the cathode 😛 and also could replace older 5V direct heated diodes .
A 5V 2A rectifier (5Y3 for example) can be powered off of a 6.3V filament secondary.
Just add a 0.65 Ohm resistor in series with the filament.
The resulting slow B+ warmup might be almost as long as an indirect heated 5AR4.
Warning/Caution!
Be sure to use a Completely Different 6.3V filament secondary for the 5Y3.
Or you will have 250V, 300V 350V B+ on all of your other 6.3V tube filaments in the amplifier . . .
Snap! Fizz! Needs repair!
Just add a 0.65 Ohm resistor in series with the filament.
The resulting slow B+ warmup might be almost as long as an indirect heated 5AR4.
Warning/Caution!
Be sure to use a Completely Different 6.3V filament secondary for the 5Y3.
Or you will have 250V, 300V 350V B+ on all of your other 6.3V tube filaments in the amplifier . . .
Snap! Fizz! Needs repair!
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I suppose (am not really sure) that the 5AR4/GZ34 was intended as a plug'n play replacement for those older filament type rectifiers with better performance.
Btw, I know of at least two bigger E series rectifiers than (but not as common as) the GZ34, the Telefunken EZ150 and the East German EYY13.
Please remember that E series indirectly heated rectifers (with the exception of the EZ4) exactly were designed to be operated from the same heater winding as all the other tubes, unless Eb doesn't exceed the heater to cathode voltage ratings.
Best regards!
I trust all current production tubes,
I trust that they will all meet or exceed their specifications.
Actually I do Not trust all of them.
The truth be known, some of them can not meet the specs of the original tubes of that type.
Quality is often missing from modern manufactured tubes.
Just my opinion.
I trust that they will all meet or exceed their specifications.
Actually I do Not trust all of them.
The truth be known, some of them can not meet the specs of the original tubes of that type.
Quality is often missing from modern manufactured tubes.
Just my opinion.
You are ALL missing the point.
Direct heated rectifiers were made 5V filaments so you were FORCED to wind a SEPARATE, EXCLUSIVE winding for them, since it HAS to be insulated at least 1kV away from anything else.
That also ensures that you are not tempted to hang any 6.3 or 12.6 V tube (all others in the amp) from that "available" filament winding.
Reason being that .... ummmmmm .... that filament sits 300-400-500V away from Ground.
It´s not a "leftover", "historic", "lazyness", whatever reason but had SOLID reasons behind it.
And don´t compare it to indirect cathode rectifiers I see mentioned above.
Apples and oranges.
Since you write that we are ALL missing the point, you must be very sure about this. Do you have a source that confirms these SOLID reasons behind it?
I do not think it is likely that 5 V was chosen with what you describe in mind. It would mean that people were dumb enough to connect a direct heated rectifier to the filaments of other tubes but at the same time were smart enough to wind their own transformers.
I do not think it is likely that 5 V was chosen with what you describe in mind. It would mean that people were dumb enough to connect a direct heated rectifier to the filaments of other tubes but at the same time were smart enough to wind their own transformers.